The present invention relates to a sliding member comprising an overlay layer made of Bi (bismuth) or a Bi alloy.
The present invention relates to a sliding member comprising a bearing alloy layer and an overlay layer using Bi or a Bi alloy which is formed on the bearing alloy layer.
In internal-combustion engines of motor vehicles, for example, there have been used sliding bearings with utilization of a copper-based or aluminum-based bearing alloy, on each of which usually an overlay layer is formed to improve conformability. The overlay layer has been conventionally made of a soft lead alloy or in some cases, an Sn alloy.
However, it is preferable not to use Pb because Pb is an environmental pollution substance, if it is possible to do so. Thus, various researches and developments have been conducted heretofore, for example, there is proposed the use of Bi or a Bi alloy instead of the Pb alloy in JP-A-2001-20955.
However, when the overlay layer of Bi or the Bi alloy is formed by electroplating because Bi lacks malleability, it is hard to make it thick. Therefore, in the case where the overlay layer is formed with Bi or the Bi alloy, there arises a problem that it is inferior in wear resistance property.
The present invention has been achieved under the above-mentioned background.